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Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
Great article, it confirms what most of us would know, but too impatient to achieve :)
My first coil had this exact same corona skirt, and it had 5 layers of varnish. (see attached photo)
The coil I am working on know is a small audio sstc, the secondary have gotten 4 layers of ship varnish applied with a paint brush. Its not quality work as the surface of the varnish is uneven and have small ripples at certain places, I suspect it to be too thick layers of varnish applied at a time.
I sure will find the time and patience to do a good varnish job on the secondaries for my upcoming vttc and sgtc.
Now we already are talking about varnish,
do you recommend spray or brushing?
few thick layers or many thin?
how often should I sand it down, and what is the best method of getting an even surface when sanding?
Banned on 3/17/2009. Registered Member #487
Joined: Sun Jul 09 2006, 01:22AM
Location:
Posts: 617
Or, if you don't want to spend your life sanding and recoating and drying. Get some glaze coat furniture epoxy. link
It works great. Mix equal parts, scoop it on with a business card and rotate it while drying. In the weather we have here it dry to the touch in a few hours and fully cures in 72. It is equal to 60 coats of varnish but is much more durable. No sanding required. One coat and you're done. A little goes a long way as well.
Registered Member #15
Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068
Dr. Spark wrote ...
Henry wrote up this website and thought it would be a great article to post.
Very interesting indeed.
This coil was in the last three W.W.T.'s and kicks butt, but now 6 more inches added in spark with just recoating the secondary. Happy reading. Rgs, Ch
Actually, thats a bit misleading. According to the article 6 more inches were added because the 1" spacer was removed from the secondary and coupling was increased between primary and secondary. Sure, the increased insulation reduced corona which decreased "racing sparks" and allowed you to increase coupling, but effectively, it was the increase in coupling that gave you better performance.
wrote ...
Great article, it confirms what most of us would know, but too impatient to achieve :)
My first coil had this exact same corona skirt, and it had 5 layers of varnish. (see attached photo)
The coil I am working on know is a small audio sstc, the secondary have gotten 4 layers of ship varnish applied with a paint brush. Its not quality work as the surface of the varnish is uneven and have small ripples at certain places, I suspect it to be too thick layers of varnish applied at a time.
I sure will find the time and patience to do a good varnish job on the secondaries for my upcoming vttc and sgtc.
Now we already are talking about varnish,
do you recommend spray or brushing?
few thick layers or many thin?
Your coil is a CW type coil which already has a very high coefficient of coupling. You aren't going to get any noticeable performance increase with this type of coil regardless of how many coats of varnish you put on it.
Registered Member #160
Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938
What this adds up to is that by increasing the insulation you are able to increase coupling thereby getting better performance, exactly like in the case of immersing the secondary of a magnifier in oil. Recently, I also spent about three weeks coating my new 6" secondary, and just to look at it makes it worth while. It has a beautiful sheen. Thanks Chris for sharing.
Registered Member #15
Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068
Chris,
I'm not sure why you think every post that doesn't necessarily agree with your statements is a personal attack on yourself. I am merely pointing out that your original statement, "...but now 6 more inches added in spark with just recoating the secondary" is somewhat misleading as it leads the reader to believe that simply recoating the secondary magically added 6 more inches, when in fact, it was the fact of increasing coupling that gave you the performance burst, which yes, better insulation of the secondary allowed you to do this as you stated.
Please stop taking every post so personally. That is certainly not my intent and should not be taken as such.
We are all in this hobby together so there is no need to start a pissing match everytime someone doesn't necessarily agree with you.
[MOD EDIT: Removed an accidental double post by myself]
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Corona Discharge vs. Coatings of Insulating Varnish on the Secondary
